One of the mysteries of the English language finally explained.
1with object And without object. To concentrate more closely or intensively.
2with object And without object. To concentrate again or further; to refine.
Early 17th century; earliest use found in James Mabbe (d. ?1642), translator. From re- + concentrate (although this is apparently first attested later), in sense 1 after Spanish reconcentrar to concentrate more closely or intensively, to confine in a small space.
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